Markopoulou: Time is Fundamental, Space is Not

The Foundational Questions Institute has run an essay contest on "The Nature of Time" and received a wide variety of responses. These come from well known physicists, other academics, and amateurs alike. Because of time contraints I've only read a few, beginning with authors I recognized (there are likely some "diamonds in the rough" if one plows through all the contributions).

Fotini Markopoulou of the Perimeter Institute, whose work I mentioned in the last post (and several older ones), wrote: "Space does not exist, so time can." She has a talent for writing clearly about these deep concepts, and I find her arguments persuasive (even if her work toward a full theory of quantum gravity still has a long road ahead). So I highly recommend the essay.

Kudos also to cosmologist and blogger Sean Carroll for his nice essay: "What if Time Really Exists" (here is the Cosmic Variance post introducing it). While I don't like some of his specific suggestions (associating time's arrow with macroscopic entropy considerations), I liked the stance he takes in the essay.

For countervailing views you can read the contributions of Carlo Rovelli and Julian Barbour.

UPDATE (7 January 2009): I just found this interesting post by Scott Aaronson - "Time: Different from space" which includes his computer science-derived insight on why time (causal structure)is fundamental.

Aether Makes a Comeback

The nineteenth century version of the ancient concept of the aether (or ether) was killed by the Michelson-Morley experiment and the success of Einstein’s theory of special relativity. Electro-magnetic radiation needed no substance to support wave propagation. Of course we did not revert to a view of space as an void sprinkled with a few solid objects. In modern particle theory, space-time is pictured as filled with matter fields. And in general relativity, space-time is revealed as a dynamic actor, not just a backdrop. Still, space-time remains distinct from matter/energy, and is geometric, rather than substantive. It thus retains a bit of the conceptual flavor of an empty container (a related discussion on the blog is here).

I was surprised to see the number of physics papers on arxiv which invoke the concept of aether (or ether) in the context of theoretical proposals to solving outstanding problems (e.g. dark energy). For me, aether was brought to mind by certain quantum gravity research programs.These propose that the space-time of general relativity is not fundamental: it emerges (along with the matter fields of the standard model) from something more basic – an underlying network of elementary quantum systems. This underlying network is not itself defined against a spatial backdrop and lacks the usual notions of distance or locality. Both space-time geometry and matter as we know them are constituted by the quantum systems: they arise from the aether.

For an example of this kind of work, here’s the second “quantum graphity” paper from Fotini Markopoulou and colleagues (the authors do not invoke the term aether, so don’t blame them!*). The introduction does a good job of discussing the stance they are taking toward the space-time of general relativity, and places this in the context of how other quantum gravity research programs approach the issue.

* Although they do link their work to the model described in this paper: “Quantum ether: photons and electrons from a rotor model” by Levin and Wen.

{UPDATED 19 November, 2008: Minor edits; 8 December 2008: Sean Carroll at Cosmic Variance just posted about his collaboration on aether field models.}

Ruminating on Theism and Personhood

As I’ve discussed in previous posts (see list below), one can try to put a theistic spin on my concept of the necessarily existing metaphysical “megaverse”: one can identify the megaverse with “God”. To be sure, it would be a non-traditional concept of God compared with that of our Western religious traditions – it would be a variety of panentheism (or perhaps panendeism). But perhaps this is simply stretching things too far, and using the label “God” is simply incongruous. Certainly there may be less room for confusion in communicating the ideas if one leaves “God” out of it (I think the historical reception given to Whitehead’s process metaphysics is a cautionary tale in this respect). While there are several considerations here, I think this decision of labeling should be driven in part by the question of personhood, which seems to be an important component of most conceptions of God.

I have a longstanding skepticism about the attribution of personhood to God -- if personhood means something similar to what it means in the human context. In the context of traditional religions, I always suspected anthropomorphism was at the root of this attribution. In outlining my version of the cosmological argument for a necessarily existing entity, I disliked even using the term “necessary being”, because it has the flavor of “human being”, and thus too readily invokes personhood.

Despite this skepticism, the panentheistic version of my view would say that human characteristics arise from the same raw materials which also constitute God, so there must be some essential affinity. Given my specific opinion that first-person experience is rooted in the most fundamental level of reality, I suspect that God might well be a subject of experience – a key aspect of human personhood.

On the other hand, when discussing Timothy O’Connor’s book (here and here), I disagreed with him on whether the necessary being (NB) needed to be considered an agent (and agency seems to be another key aspect of personhood). It seemed sufficient for the NB to be an impersonal font of creation without need of intentions, purposes, or discrete top-down decision-making. My thought here is that a human being moves within a sea of other beings or systems, and his/her agency arises in this context. The NB is the source and sum of all being, and does not operate in a larger context. This seems to me to be an important difference. To use an analogy: if a human being is an actor, then God is the theater, not another actor.

So, at this point I have a mixed verdict – our human essence is derived from the NB, but our status as a finite subset of the NB’s totality makes our nature very different. Whether the concept of personhood can be stretched to cover both situations is unclear, and I think the better option is to decline to consider the NB to be a person. And this may be a good reason to resist using the label God for what I have in mind.

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Note: I’m even less well-read in relevant literature in this area than in other subjects I discuss: any reading suggestions in philosophy of religion are welcome.
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Post Series (in chronological order): A Philosophical Path to Theism?

Modal Realism and the Cosmological Argument
Exploring the Borderlands
Panentheism
Whitehead's Philosophical Theism
Logos vs. Chaos, Part One
Logos vs. Chaos, Part Two
A Necessary Being or Just a Collection?
Why the Megaverse is a Unified Entity
Is the Megaverse a Subject of Experience?

Finally! (off-topic post)

28 years since the last Phillies championship and 25 years since the last city title in a major sport.

And what a great team. They are a well rounded, solid group of players, with stars we've seen develop over the years as well as clutch role players added recently. Great personalities who've given us wonderful entertainment and now the most satisfaction a fan can get.

Ryan Howard's victory lap -- picture by elisbrown -- flickr under creative commons license.

What Lies Beyond the Big Bounce

We don’t have a fully developed theory of quantum gravity yet, but there is one consequence of the theory we already know: it will banish general relativity’s space-time singularities from our conception of the universe. In particular, the idea of the big bang needs to be retired after decades of dominating professional and popular views of cosmology: the observed universe did not begin as a singularity but rather grew out of a pre-existing reality – a “big bounce”.

Martin Bojowald had a nice article in SciAm recently ("Follow the Bouncing Universe" in the print edition). Bojowald is a loop quantum gravity theorist: while loop theory has not produced an adequate theory for quantum gravity (and I think it probably won’t), it has produced formalisms that may be useful for constructing models which offer insight into the question of what will replace singularities in QG. This work goes under the rubric “loop quantum cosmology (LQC)”. I also noticed that Bojowald’s senior colleague Abhay Ashtekar has a paper out summarizing the results of work in LQC.

What intrigues me is their exploration of what the region on the other side of the big bounce might be like.

In his article, Bojowald first outlines the idea that space-time in QG is not a continuum, but rather has a fine-scale fundamental structure. These space-time “atoms” follow the rules of quantum mechanics and therefore the physics that prevails at high energies/short distances will differ from general relativity (GR). Specifically, in the loop model, a repulsive force comes into play at high energy densities, preventing singularities. In the case of the big bang, one scenario is that the initial high density state arose when a pre-existing universe collapsed (hence – a “bounce”). Bojowald describes an early, simplified, model which seemed to imply that the pre-existing universe was similar to our own. However, Bojowald says his own subsequent work found that quantum effects would have dominated the immediately pre-existing world:

“So the bounce was not a brief push by a repulsive force, like the collision of billiard balls. Instead, it may have represented the emergence of our universe from an almost unfathomable quantum state – a world in highly fluctuating turmoil.”

Bojowald finishes by discussing how we might learn more about the pre-existing universe from astronomical clues.

Ashtekar’s paper discusses the same research more formally; in addition he also deals with LGC models for black holes, where again singularities are replaced by quantum regions (somewhat surprisingly to me, black holes are somewhat more difficult to model than the big bang itself). He concludes his discussion of the big bang/bounce this way: “Big bang is not the Beginning nor the big crunch the End. Quantum space-time appears to be vastly larger than what general relativity had us believe!”

My takeaway is that a realm of quantum possibilia extends beyond and surrounds us our island of observable cosmos. The old idea of the universe as a relatively straightforward, neatly bounded space-time container must be discarded.

The Intentionality of the Single Cell

I highly recommend this paper by Tecumseh Fitch. In it he traces the distinctive intrinsic intentionality of the mind to the capabilities of the eukaryotic cell -- which he calls "Nano-Intentionality". Hat tip to this post at Conscious Entities (although Peter was less impressed than I was with the core argument).

Paper on Entanglement in Biology

Through a search on arXiv I found a paper by Hans Briegel and Sandu Popescu called “Entanglement and intra-molecular cooling in biological systems? – A quantum thermodynamic perspective”. It made what struck me as a straightforward case for why non-trivial entanglement is plausible in a biological context, given that living things are open thermodynamical systems. The paper’s goals are modest: it does not present experimental results but just describes some toy models which motivate their argument. The authors believe research needs to be directed towards searching for signatures of entanglement in biological systems.

The authors do mention in passing that they think coherence on a very large scale, such as across the whole brain, is “virtually impossible”. If true, this implies that if brain processes exploit quantum effects, it is as a result of aggregation of such effects at the sub-cellular level.

As an aside, here’s the URL for the search I did on arxiv. This obviously only captures a small slice of what might be happening in this area, and specifically tilts toward the theoretical rather than experimental side of things. My unscientific impression is most of the papers here are being authored outside the United States. Hopefully a concrete result such as last year's detection of quantum effects in photosynthesis at Berkeley will accelerate research in this area everywhere.

2008-2009 GPPC Program

Here's a link to the Greater Philadelphia Philosophy Consortium's program for this year (the GPPC is a cooperative effort by 15 area universities to sponsor philosophy conferences and other programs). There is also a regional calendar which includes some other events taking place at member schools - the great majority are open to the public.

I'm looking forward in particular to the November 22 event at Swarthmore, "New Approaches to the Mind/Body Problem," which will feature talks from the phenomenological perpective on mind from Barnard College's Taylor Carman and Oregon's Mark Johnson.

Is the Megaverse a Subject of Experience?

My thanks to Justin, whose comment and question on the last post is prompting me to try to clarify some of my thinking.

Below I address his question of whether this “megaverse” I’ve discussed in the last couple of posts might be a cosmic-level subject of experience, given our shared endorsement of panexperientialism in the context of philosophy of mind. I tentatively think the answer is yes. Along the way I’ll try to better explain some of my reasoning and my use of terms.

The most common conception of the universe people have via science is that of a space-time container with matter/energy inside it. I’ve come to believe that this conception is wrong. I think it is likely that space-time itself is not a fundamental entity, but co-emerges with matter from a more fundamental level of quantum causal events. And the universe we see is only a slice of something larger (there are no boundaries – quantum gravity models imply that the big-bang was not a singularity, but arose from a pre-existing context).

So what we think of as the actual universe is an arbitrary slice of a larger reality, and it therefore doesn’t have a good claim to be a unified whole or a candidate for being a cosmic experiential subject.

What lies beyond our actual universe? Various motivations have led cosmologists as well as philosophers to propose the existence of many worlds or universes -- a multiverse. If these are completely separate worlds, then their existence would seem to have no impact on ours, but they might help explain the appearance of contingency and fine-tuning in ours. I’d note that the multiverse conception at first doesn’t seem to fit well with the idea of our universe as a cosmic subject – unless there is one such subject for every universe.

Again, though, what we call the actual world is not some space-time container with stuff inside, it is just the causally connected region or nexus we find ourselves in. So then it is wrong to think of the multiverse as a collection of distinct space-time containers. Even if we have not been in causal contact, these other parts of reality should not be thought of as completely separate realms. I’ve taken to calling this total reality the “megaverse” rather than the multiverse, given this way of thinking.

When thinking about the nature of this megaverse, I’ve connected it to my philosophical thinking on modal realism and causality. My modal realism leads me to identify the megaverse with the complete set of metaphysical possibilities (going beyond the multiverse motivations of physicists/cosmologists). My preferred model of causality leads me to see a close relationship between each actual event and the possible but not actual events which are also part of the megaverse. (Note also because “actual” just denotes “local” in this model -- actual is an indexical term -- what is an actual event vs. a possible event is not a fundamental distinction. All events are on an even footing.)

So, I’ve given the name megaverse to this largest conception of reality, and I see it as a holistic entity given the interdependence of its constituent-events. Let me come back, then, to the question of postulating a cosmic experiential subject: if all events have an experiential aspect, then it makes sense that the holistic network of all events is also the subject of (all) experiences. I’m not sure this makes the megaverse something which has consciousness or agency in a way analogous with the human variety. This is something to think further about.

Why the Megaverse is a Unified Entity

To continue the discussion from the last post, I sketch below some reasons why the metaphysical “megaverse” – the sum of all actual and possible events – should be considered a unified whole rather than a “mere” collection.

First, while I realize the field of mereology has been contentious for ages, I have always favored arguments that a whole is more than the sum of is parts (composition is not identity). I have several posts dealing with this in the context of trope theory: it appears that tropes cannot be bundled without an external unifier (I discussed Bill Vallicella’s arguments on this topic here and in the second half of this post). What could unify objects? The best answer IMO comes in terms of a theory which approaches composition via causation (see the paper discussed here for why this is a promising approach).

Moving specifically to my preferred event ontology, I think that participation in a larger causal pattern serves to unify constituent events into higher-level units (event complexes). Gregg Rosenberg’s theory on causation and natural individuals serves as an example of this approach (discussed here and here). To extrapolate, we can picture a hierarchy of causal patterns culminating in the largest one of all – the megaverse.

Further, because individual micro-level events in this model are actualizations drawn from a set of possible events, they simply cannot exist in isolation. The existence of an actual event presupposes a space of possibilities. I believe quantum physics provides a posteriori evidence for this feature of reality.

There are other possible arguments for the unity of the megaverse. For instance, the megaverse serves to ground necessary truths (such as those of arithmetic and basic logic). These truths extend throughout the megaverse, providing a unifying “shape” to events.

Also, the megaverse supports consciousness. In my preferred theory of mind, causation is inherently experiential, and the unification of constituent experiences is a defining characteristic of consciousness.

Much more can and should be said, but I think the case is good for considering the necessary existent to be a unified entity.